The present invention relates to flexible covers or tarping systems for open-topped containers. The invention is particular related to tarping systems for use with hauling vehicles, such as dump trucks, where the flexible cover or tarpaulin is extended across the open top of the truck body.
Many hauling vehicles, such as dump trucks, include open-topped containers useful for hauling or storing various materials. For example, in a typical dump truck application, the dump body is used to haul a variety of particular material, such as gravel, aggregate or similar products. In addition, some hauling vehicles carry organic materials, such as grain or produce.
Depending upon the nature of the materials stored in the open-topped container, it is often desirable to provide a cover for the container. Of course, rigid covers are well known that may be hinged from end of the container body. These rigid covers have gradually given way in the trucking industry to flexible tarping systems because the flexible tarpaulin can be easily stowed when a cover is not necessary, such as when the dump truck is being loaded. Moreover, the flexible tarp is much easier to deploy than a rigid cover, and is easier to replace when it becomes worn or damaged. Furthermore, in some instances the flexible tarp provides a tighter environmental seal for the contents of the container than is provided by a rigid cover.
A variety of tarping systems have been developed that are geared to particular hauling vehicle applications. Once such tarping system for use with dump trucks is the Easy Pull(copyright) tarping system of Aero Industries, Inc. The Easy Pull(copyright) system includes a flexible tarp that is wound around a spool at one end of a dump bed. A rope attached to the free end of the tarp can be used to unwind the tarp from the roller to extend along the length of the dump bed.
Another cover system particularly suited for open-topped containers on hauling vehicles is the Easy Cover(copyright) tarping system, also of Aero Industries, Inc. The Easy Cover(copyright) tarping system includes a U-shaped bail member that is pivotally mounted at its end to the base of the container body. The horizontal section of the U-shaped bail is attached to the tarp, while the free ends of the vertical elements are pivotably mounted to the truck body. In one application, the Easy Cover(copyright) tarping system allows the tarp to be manually pulled in a sweeping arc over the container load.
In another application of the Easy Cover(copyright) system, an actuation mechanism is provided that automatically pivots the U-shaped bail member to deploy the tarp over the load within the open-topped container. When the actuation mechanism is released, it automatically pivots the bar, thereby unfurling the tarp from the tarp roller at the front of the vehicle. A hand crank or powered motor can be provided to rotate the tarp roller to retract or wind the tarp when it is desired to open the container top.
A vehicle 10 is depicted in FIG. 1 having an open-top dump body 12. As illustrated, the vehicle can be a dump truck, with the open-topped container comprising a dump body. A flexible cover system 14 mounted on the body 12 includes a tarpaulin cover 15 that is shown in its deployed position spanning the length of the container and covering the load within. The tarp cover 15 can be wound onto a retraction mechanism 19, which can be in the form of a roller assembly, such as employed in the Easy Cover(copyright) tarping system.
Referring still to FIG. 1, an extension mechanism 17 is utilized to pull the tarp 15 across the container body 12. In the illustrated embodiment, the extension mechanism 17 includes the U-shaped bail member described above. However, for the purposes of the present invention, the extension mechanism 17 can be a variety of types of mechanisms, whether motorized or manual, and whether relying upon pivoting bail arms or longitudinally driven members. However, for the purposes of illustration of the principles of the present invention, a rotatable spring-biased extension bail member is illustrated.
With this illustrated embodiment, the extension mechanism 17 is spring biased so that its natural tendency is to pull the tarp out of the retraction mechanism 19. Again, for purposes of illustration, the retraction mechanism 19 can include a drive motor 20 that rotates a spool 21 or roller to which one end of the flexible tarp 15 is fastened.
With reference to FIG. 2, one difficulty of prior flexible tarpaulin cover systems is illustrated. The container body 12 in this figure includes a top rail 22. A cab shield 26 extends above and forward of the top rail 22 to support the retraction mechanism 19. In one application, the body 12 includes sideboards 24 that extend the length of the container body. The flexible tarp 15 is shown extending over at heaped load L. As shown in FIGS. 1 and 2, the flexible tarp 15 is held in an extended position 28 or 28xe2x80x2. In the case of the extension mechanism 17 shown in FIG. 1, the mechanism itself holds the tarp at its extended position 28. In the configuration illustrated in FIG. 2, the flexible tarp is held in the extended position 28xe2x80x2 by a tie-down arrangement. At any rate, when the tarp 15 is fully extended over the length of the container 12 and covering the load L, a gap can exist between the tarp 15 and the interior of the container body, as depicted in FIG. 2.
A similar problem exists where the sideboards 24 are not used. In this instance, a heaped load Lxe2x80x2 extends slightly above the top rail 22. The flexible tarp 15xe2x80x2 then covers the heaped load Lxe2x80x2 in its extended position 28xe2x80x2. Again, as can be seen in FIG. 2, the tarp 15xe2x80x2 has a gap between it and the top rail 22.
In order to eliminate this gap, extra tarp 15 can be payed out from the retraction mechanism 19. With this approach, the tarp will fall over the load L, Lxe2x80x2. However, when the container body 12 is on a moving vehicle, such as a dump truck, the wind and vibration generated at traveling speeds causes the tarp 15, 15xe2x80x2 to flap and expose the load beneath.
Various solutions have been devised to help hold the excess tarp material down over the load L, Lxe2x80x2 when the tarp is in its extended position 28, 28xe2x80x2. For example, in U.S. Pat. No. 4,341,416, a linkage and side flap arrangement is employed. With this approach, the tarp includes side flaps that are held against the outside of the truck body by a specific external linkage arrangement.
Another approach is illustrated in U.S. Pat. No. 5,031,955. This approach is limited to use with tarp extension mechanisms utilizing an external bail arm. In this approach, a tension bail arm is pivotally mounted to the extension bail arm. The tension bail arm extends across the outside of the truck body to hold the front portion of the flexible cover down.
Yet another approach is described in pending U.S. application Ser. No. 09/330,143, filed Jun. 11, 1999, by Aero Industries, Inc. and entitled xe2x80x9cTarp Cover Hold-Down Systemxe2x80x9d. The system disclosed in this application, which disclosure is incorporated herein by reference, includes a U-shaped bar that resides within the interior of the container body. The bar is spring biased by torsion springs so that it pivots downward to provide a downward force against the front portion of the flexible cover. With this mechanism, the torsion spring applies a constant downward pressure directly on the tarp within the interior of the container body, so that its effectiveness is not limited by the sideboards or rails of the container.
While the system of the ""143 Application represents a significant advance in devices for holding a tarp down, it too has its drawbacks. For instance, the disclosed mechanism requires the mounting of an additional component to the container body or to the retraction mechanism. In addition, the hold-down bar of the mechanism must be retracted against the retraction mechanism or roller. Since the bar is spring-biased, it is constantly exerting a downward force against the tarp as it is being deployed to its extended position or retracted to its stowed position. This downward force, coupled with the continuous contact by the bar, can cause additional wear to the flexible tarp.
Consequently, there remains a need for an improved mechanism for holding a flexible tarp down in its extended position. The system must be capable of keeping the cover tightly down over the load L, even against road vibration and wind force generated when traveling at highway speeds. In addition, the improved system would be easily installed, and potentially capable of retrofit to existing flexible tarping systems.
In order to address these unresolved needs, the present invention provides a cover system for an open-topped container comprising a flexible cover having a first end and an opposite second end, a retraction mechanism connected to the flexible cover at the first end for retracting the cover to a retracted position relative to the container, and an extension mechanism connected to the flexible cover at the second end for extending the cover from the retracted position to an extended position spanning at least a portion of the open top of the container. In a central feature of the invention, a weighted element is carried by the flexible cover between the first and second ends. The weighted element has a weight sufficient to pull the flexible cover down by the force of gravity when the cover is in the extended position.
In certain embodiments, the retraction mechanism can include a spool and means for winding the flexible cover onto the spool. In these embodiments, the weighted element is sized and configured to be wound onto the spool with the flexible cover. Preferably, the weighted element includes at least one weighted bar extending across a portion of the width of the cover. The weighted bar has a width and a thickness sized to permit the weighted bar to be wound onto the spool with the flexible cover.
In the most preferred embodiments of the invention, the flexible cover includes a pocket extending across a portion of the width that is sized to carry the weighted element. Where the weighted element is a bar, the pocket can be appropriately configured. The pocket can be closed around its perimeter to generally permanently house the bar therein. Alternatively, the pocket can be provided with an open end and a flap covering that end. The flap can be displaced to allow insertion or removal of a weighted bar from the pocket.
In some embodiments, the weighted element includes a plurality of weighted bars within a corresponding plurality of pockets. The plurality of pockets and bars can be concentrated at the one location adjacent to the first or front end of the tarp. Alternatively, the pockets and bars can be distributed at locations along the length of the tarp.
Where a single weighted element is implemented, it can be offset from the first end of the tarp by a predetermined dimension so that the weighted element pulls the flexible cover below a top edge of the container when the cover is in the extended position. This predetermined dimension can be adjusted as needed depending upon the configuration of the container. For instance, a dump body having the retraction mechanism mounted on a cab protector requires a certain lag length of tarp to reach the top rail of the dump body. This lag length can be shorter if the dump body includes sideboards.
The weight of the weighted element is calibrated to hold the front end of the tarp down when subject to vibration and wind during over-the-road travel. In a specific embodiment, the weighted element can have a weight of at least ten pounds (about 4.5 kg.). In one aspect of certain embodiments, a retention mechanism can be provided on the container body to help hold the weighted element in place once gravity pulls it and the tarp down. This retention mechanism can be a magnet mounted on the container that magnetically attracts the weighted element.
In an alternative embodiment, the weighted element, and particularly the weighted bars, are attached to the tarp or flexible cover, without the need for the pockets. With this embodiment, the tarp can be provided with grommets for receiving a fastener, such as a nut and bolt arrangement. The weighted element can be provided with holes to receive the bolt, or can have one of the nut or bolt components integrated into the element itself.
Another aspect of the invention contemplates a cover for a cover system for an open-topped container, in which the system includes a retraction mechanism mounted to the container and a extension mechanism. The cover comprises a flexible tarpaulin sized to substantially close the open top of the container when extended, and a weighted element carried by the tarpaulin and having a weight sufficient to pull the flexible tarpaulin down by the force of gravity when the tarpaulin when extended. The tarpaulin can be provided with a number of pockets for carrying the weighted element, which is preferably in the form of individual weighted bars.
In yet another embodiment of the invention, a flexible tarpaulin is provided that is sized to substantially close the open top of a container when extended. The tarpaulin has a first end configured for engagement to a retraction mechanism and an opposite second end configured for engagement to an extension mechanism of a cover system for the container. In one feature of this embodiment, the tarp includes a pocket extending across a portion of the width of the tarpaulin adjacent but offset from the first end thereof. The pocket is sized to receive a weighted bar therein. The tarp can be provided with a plurality of pockets at the first end thereof, or can include a plurality of pockets at a plurality of spaced locations along the length of the tarpaulin.
One object of the present invention is to provides a system for holding a tarp down over a load within a container, even when the tarp or flexible cover is subject to road vibration and wind. One benefit is that this xe2x80x9cgravity-biasxe2x80x9d feature of the present invention is provided without the need for additional hardware mechanisms mounted on the container or integrated into the tarping system itself. In prior systems, this additional equipment can take a beating during normal use, which damages the equipment and eventually requires pre-mature replacement.
A further benefit of the invention is realized in features that allow the invention to be retrofitted to existing tarping systems. These and other benefits and objects of the invention will be appreciated upon consideration of the following written description and accompanying figures.